Double binocular spectacles, per se, are known, Proposals for such devices appear in the Patent Literature, mostly of a relatively ancient date. A typical example is U.S.Pat. No. 1,562,046. This discloses double binocular spectacles whose purpose is to provide a microscopic or magnifying instrument in which an object may be viewed under considerable magnification and in the proper field of vision of both eyes at a substantially greater distance from the eyes than is possible with a simple magnifying glass such as commonly used by surgeons, watchmakers or others dealing with small objects which have to be seen magnified for proper manipulation. The double binocular spectacles thus act as a head-mounted microscope.
Various designs for similar optical devices exist. These can generally be recognised by the fact that the objective lenses (i.e. those furthest from the eyes of the wearer) are smaller than the eyepiece lenses, and are usually spaced apart from one another laterally by an amount which is less than the lateral spacing of the eyepieces. This arrangement is required in order to generate a focal point for both eyes in the close distance range. Some designs, for example that disclosed in U.S. Pat. No. 945,078 (patented 4 Jan., 1910) stressed the importance of having small objective lenses, so that these do not interfere with overall vision, whereby the user can look around freely and "do all kinds of work without the glasses interfering, or without the necessity of removing the glasses from the face, in view of the fact that it is possible to look over, under, or at the sides of the glasses".
U.S. Pat. No. 2,978,955 (patented 11 Apr., 1961) discloses a clip-on frame arrangement for providing a double binocular magnifying device.
European Patent Specification 0178014A (published 16 Apr., 1986) discloses spectacles in which the primary lenses are formed with holes designed to receive a sleeve which then contains an auxiliary lens. GB 2194646A (published 9 Mar., 1988) discloses a variety of constructions the overall result of which is essentially the same as that of EP 0178014A, in that a small central region of the eyepiece lens is provided with a magnifying attachment.
From the foregoing, it will be appreciated that the double binocular spectacles proposed hitherto have been based upon the notion that it is desirable to view small objects under magnification, but at a comfortable distance away from the eye. The binocular optical axes of such devices therefore tend to be strongly convergent.
Home entertainment has increased substantially over the last twenty years. Audience research figures show that television programs occupy a substantial proportion of most families' leisure time. It is normal for television to be watched by one or more members of a family for five or more hours per day. With the increasing popularity of home video recorders, the range and quantity of material available for home entertainment has increased dramatically. Alongside this remarkable increase in home entertainment, attendances at cinemas have declined.